CNN
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Missouri carried out the first known US execution of an openly transgender person Tuesday when Amber McLaughlin, who was convicted of a 2003 murder and unsuccessfully sought clemency from the governor, was put to death by lethal injection.

“McLaughlin was pronounced dead at 6:51 p.m.,” the Missouri Department of Corrections said in a written statement.

“I am sorry for what I did,” wrote McLaughlin in her final statement, which was released by the department of corrections. “I am a loving & caring person.”

McLaughlin’s execution – the first in the US this year – is unusual: Executions of women in the United States are already rare. Prior to McLaughlin’s execution, just 17 had been put to death since 1976, when the US Supreme Court reinstated the death penalty after a brief suspension, according to the Death Penalty Information Center. The non-profit organization confirmed McLaughlin is the first openly transgender person to be executed in the United States.

McLaughlin, 49, and her attorneys had petitioned Republican Gov. Mike Parson for clemency, asking him to commute her death sentence. Aside from the fact a jury could not agree on the death penalty, they say, McLaughlin has shown genuine remorse and has struggled with an intellectual disability, mental health issues and a history of childhood trauma.

But in a statement Tuesday, Parson’s office announced the execution would move forward as planned. The family and loved ones of her victim, Beverly Guenther, “deserve peace,” the statement said.

“The State of Missouri will carry out McLaughlin’s sentence according to the Court’s order,” Parson said, “and deliver justice.”

McLaughlin – listed in court documents as Scott McLaughlin – had not initiated a legal name change or transition and as a death-sentenced person, was kept at Potosi Correctional Center near St. Louis, which housed male inmates, McLaughlin’s federal public defender Larry Komp and the governor’s office have said.

McLaughlin was sentenced to death for Guenther’s November 2003 murder, according to court records.

The two were previously in a relationship, but they had separated by the time of the killing and Guenther had received an order of protection against McLaughlin after she was arrested for burglarizing Guenther’s home.

Several weeks later, while the order was in effect, McLaughlin waited for Guenther outside the victim’s workplace, court records say. McLaughlin repeatedly stabbed and raped Guenther, prosecutors argued at trial, pointing in part to blood spatters in the parking lot and in Guenther’s truck.

A jury convicted McLaughlin of first-degree murder, forcible rape and armed criminal action, court records show.

But when it came to a sentence, the jury was deadlocked.

Most US states with the death penalty require a jury to unanimously vote to recommend or impose the death penalty, but Missouri does not. According to state law, in cases where a jury is unable to agree on the death penalty, the judge decides between life imprisonment without parole or death. McLaughlin’s trial judge imposed the death penalty.

If Parson were to grant clemency, McLaughlin’s attorneys argued, he would not have subverted the will of the jury, since the jury could not agree on a capital sentence.

That, however, was just one of several grounds on which McLaughlin’s attorneys said Parson should grant her clemency, according to the petition submitted to the governor.

In addition to the issue of her deadlocked jury, McLaughlin’s attorneys pointed to her struggles with mental health, as well as a history of childhood trauma. McLaughlin has been “consistently diagnosed with borderline intellectual disability,” and “universally diagnosed with brain damage as well as fetal alcohol syndrome,” the petition said.

McLaughlin was “abandoned” by her mother and placed into the foster care system, and in one placement, had “feces thrust into her face,” according to the petition.

She later suffered more abuse and trauma, including being tased by her adoptive father, the petition said, and battled depression that led to “multiple suicide attempts.”

At trial, McLaughlin’s jury did not hear expert testimony about her mental state at the time of Guenther’s murder, the petition said. That testimony, her attorneys said, could have tipped the scales toward a life sentence by supporting the mitigating factors cited by the defense and rebutting the prosecution’s claim McLaughlin acted with depravity of mind – that her actions were particularly brutal or “wantonly vile” – the only aggravating factor the jury found.

A federal judge in 2016 vacated McLaughlin’s death sentence due to ineffective counsel, court records show, citing her trial attorneys’ failure to present that expert testimony. That ruling, however, was later overturned by the Eighth Circuit Court of Appeals.

McLaughlin’s execution “would highlight all the flaws of the justice system and would be a great injustice on a number of levels,” Komp, her attorney, told CNN previously.

“It would continue the systemic failures that existed throughout Amber’s life where no interventions occurred to stop and intercede to protect her as a child and teen,” Komp said. “All that could go wrong did go wrong for her.”